Research libraries have long invested in approval plan services, which offer an economical way to acquire scholarly and scientific publications. Traditional approval plans have evolved and now enable libraries to expand their e-book offerings to better serve researchers. Publishers offer a myriad of e-book purchasing options. These range from individual titles to comprehensive packages allowing libraries to choose publisher-direct (Springer and others) or aggregator (Ebrary, for example) access, but a standard access and pricing model is needed to promote systematic acquisition of e-books. In 2010, Texas A&M University Libraries implemented an e-preferred approval plan. This article will discuss the evaluation process for research libraries migrating to an e-preferred approval plan.